PM10 and PM2.5 Attainment Fact Sheet

Connecticut DEEP began monitoring for PM10 in 1984. In 1990, the U.S. EPA designated the City of New Haven as nonattainment for the PM10 standard. By 2005, as a result of local control strategies implemented during the early 1990’s, monitored levels improved to the point that Connecticut requested that EPA redesignate the City of New Haven as an attainment area for PM10. EPA approved the request in October 2005. Meanwhile, in January 2005, Fairfield and New Haven counties, together with counties in New York and New Jersey, were designated by EPA as nonattainment for the new PM2.5 standard.

PM10 Standards

The 24-hour PM10 national ambient air quality standard (NAAQS) is 150 µg/m3 with no more than one expected exceedance per year. The annual PM10 standard (previously set at 50 µg/m3, expected annual arithmetic mean) was revoked as of December 2006 due to a lack of evidence linking health problems to long-term exposure to coarse particle pollution. See Particulate Matter Fact Sheet for more information about particle pollution:

Connecticut is currently in attainment for the 24-hour NAAQS for PM10.

No violations of the PM10 NAAQS have been measured in Connecticut since the early 1990’s, at which time corrective measures were implemented in the City of New Haven to reduce localized PM10 emissions.

CT DEEP will maintain a network of PM10 monitors. If future violations of the PM10 standards occur, contingency plans will be implemented (as described in the LMP).

PM2.5 Standards

The U.S. EPA originally promulgated NAAQS for fine particulate matter, i.e. particles with a mean aerodynamic diameter less than or equal to 2.5 µm (PM2.5), on July 18, 1997. The annual average NAAQS for PM2.5 is 15 µg/m3 ("the 1997 PM2.5 standard"). The 24-hour average NAAQS was revised by EPA effective December 2006, and is 35 µg/m3 ("the 2006 PM2.5 standard").

CT DEEP designed a monitoring network and began PM2.5 monitoring in 1999.

In January 2005, EPA designated both Fairfield and New Haven Counties as nonattainment for PM2.5. They based their conclusion on the premise that these counties were contributing to PM2.5 nonattainment in New York City. Currently, Connecticut PM2.5 monitors measure levels compliant with the PM2.5 standard.